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Contract No. DE-AC36-08GO28308

Archiving Data from New Survey 

Technologies: Lessons Learned 

on Enabling Research with 

High-Precision Data While 

Preserving Participant Privacy

Preprint

J. Gonder and E. Burton

National Renewable Energy Laboratory

E. Murakami

U.S. Department of Transportation

To be presented at the 10th International Conference on Transport 

Survey Methods 

Leura, Australia

November 16-21, 2014

Conference Paper

NREL/CP-5400-62901

November 2014 
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Gonder et al. – Archiving Data from New Survey Technologies

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ABSTRACT

During the past 15 years, increasing numbers of organizations and planning agencies have begun 

collecting high-resolution Global Positioning System (GPS) travel data. Despite the significant 

effort and expense to collect it, privacy concerns often lead to underutilization of the data. To 

address this dilemma of providing data access while preserving privacy, the National Renewable 

Energy Laboratory, with support from the U.S. Department of Transportation and U.S. 

Department of Energy, established the Transportation Secure Data Center (TSDC). Lessons 

drawn from best-practice examples from other data centers have helped shape the structure and 

operating procedures for the TSDC, which functions under the philosophy of first and foremost 

preserving privacy, but doing so in a way that balances security with accessibility and usability 

of the data for legitimate research. This paper provides details about the TSDC approach toward 

achieving these goals, which has included creating a secure enclave with no external access for 

backing up and processing raw data, a publicly accessible website for downloading cleansed 

data, and a secure portal environment through which approved users can work with detailed 

spatial data using a variety of tools and reference information. This paper also describes lessons 

learned from operating the TSDC with respect to improvements in GPS data handling, 

processing, and user support, along with plans for continual enhancements to better support the 

needs of both data providers and users and to thus advance the research value derived from such 

valuable data.

1. INTRODUCTION

Departments of transportation and metropolitan planning organizations (MPOs) regularly collect 

travel survey data for purposes such as developing/updating transportation demand forecasting 

models and identifying transportation needs within a survey region. These surveys have been 

conducted for many decades and historically include mail-out/mail-back travel diaries 

supplemented by computer-assisted telephone interviews. In the late 1990s, several MPOs began 

investigating the use of Global Positioning System (GPS) technology to improve the accuracy 

and completeness of personal travel data collection [1]. Continually improving GPS accuracy 

and declining equipment costs have made it practical to include a GPS data-collection 

component in many modern surveys.

The expanded application of vehicle- and person-based GPS instruments along with other 

enabled new technologies (such as smart phone data collection) have created different 

opportunities and challenges relative to traditional diary-based and computer-assisted telephone 

interview survey techniques. The increased spatial and temporal precision of the data can help 

improve the overall quality and confidence in survey results, and it can open up new application 

opportunities for the data in both traditional and nontraditional fields [2]–[8]. However, the 

increased data precision (sufficient to identify specific house or business locations at trip ends) 

also creates an inherent privacy concern, particularly when the spatial data are linked to 

demographic information collected during the survey effort. This confidentiality issue must be 

addressed if the archived data are to provide ongoing research and analysis value.

With data-collection costs ranging from hundreds of thousands to millions of U.S. dollars per

study and limited available funding for conducting surveys, it is important to maximize each 
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study’s benefit through preserving the data and responsibly making it available for ongoing 

research. Indeed, recent years have seen growing recognition of the value of and growing support 

for “open data” policies wherever possible. A May 2013 White House Executive Order on Open 

Data Policy referenced the tremendous public value that has been derived from the decision to 

make GPS technology itself open to anyone and cited that experience as part of the motivation 

for increasing open data in government [9]. Researchers supported with federal funds must now 

create a data-management plan in advance of conducting the research. In addition, data-curation 

and institutional repositories are now considered “essential infrastructure” [10], [11].

Recognition of the value to archive and make accessible household travel behavior survey data 

led (more than a decade ago) to the creation of the Metropolitan Travel Survey Archive at the 

University of Minnesota [12]. The Metropolitan Travel Survey Archive has received intermittent 

funding from the U.S. Department of Transportation (DOT) through the Federal Highway 

Administration (FHWA) and start-up funding from the Bureau of Transportation Statistics. 

However, the aforementioned privacy concerns from transportation agencies that had 

incorporated GPS into their travel behavior studies made these agencies reluctant to include a 

copy of the GPS data in the Metropolitan Travel Survey Archive, even if only for archival 

purposes and not for data access.

In response to this open data impediment and consistent with the recommendations of a 2007 

National Research Council report about resolving the conflict between data utilization and 

confidentiality protection [13], the U.S. Department of Energy’s (DOE’s) National Renewable 

Energy Laboratory (NREL) began partnering in late 2009 with DOT/FHWA to develop a data 

center that allows access to highly detailed records of travel in time and space in a way that 

maintains respondent anonymity. Ongoing DOT and DOE support since then has established the 

resulting Transportation Secure Data Center (TSDC) [14] as one of NREL’s significant archiving 

efforts for sensitive transportation data. Others include the National Fuel Cell Technology 

Evaluation Center (NFCTEC; formerly the Hydrogen Secure Data Center, HSDC), the Fleet

DNA medium- and heavy-duty vehicle drive cycle repository, and the Fleet Sustainability 

Dashboard (FleetDASH) [15]-[17].

The remainder of this paper provides further details about the approach, structure, and contents 

of the TSDC and lessons learned through the process of developing and operating it.

2. DESIGNING THE TSDC

When developing the basic design for the TSDC, NREL and FHWA considered lessons from 

best-practice examples at other data centers. These included examples from other NREL secure 

transportation data centers (such as those mentioned above) as well as examples from analogous 

data centers, such as the Census Bureau’s Research Data Center program, with its long 

established system of providing researchers access to highly confidential data [18]. One of the 

security features noted when benchmarking the Research Data Center program was the 

requirement that users travel to specific locations to access the data. Unfortunately, even with the 

steady addition of new sites, the travel requirement presents a cost and time inconvenience for

many researchers. Further benchmarking revealed one example repository at the NORC Data 

Enclave that permitted restricted remote access for researchers. This enclave stores social science 
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micro-data records, such as those from the Annie E. Casey Foundation’s Making Connections 

Survey on topics including economic hardship in families and those from a National Science 

Foundation Survey of Earned Doctorates [19]. Another recent virtual research data center 

example provides access to sensitive Medicare and Medicaid program data [20].

For the TSDC approach, NREL and FHWA decided that the availability of secure remote access 

to a single data center would give the greatest benefit to both data providers and users. On the 

provider side, this relieves the burden from each MPO or transportation agency of having to store 

and protect data, respond to data-sharing requests, and/or set up their own secure data center. 

Users also benefit from not needing to travel, from finding data in a single location, and from 

working with data they would not otherwise be able to access. As described later, accomplishing 

this vision required implementing technical controls to prevent removal of data through the 

remote connection and providing appropriate tools on the remote site for use in conducting 

analyses.

An important step in the TSDC development process was establishing an advisory group to help 

provide oversight, to give technical input, and to represent the interests of various stakeholders. 

This group includes data providers and users who work in industry, academia, and government. 

Input from the advisory group helped drive the TSDC development philosophy to first and 

foremost implement security measures for protecting data and preserving participant privacy. At 

the same time, advisory committee members representing the user community help ensure that 

protections are implemented in a way that still permits researchers access to critical data 

elements in the most user-friendly manner possible (while working within the privacy-protection 

constraints).

Consultation with the advisory group on how to best strike the balance between privacy 

protection and usability led ultimately to organizing the TSDC into three distinct sections: (1) a 

secure enclave for raw data (with no external access), (2) a public download area for cleansed 

data, and (3) a secure portal environment for controlled access to detailed data. For the first level 

of external access through the public download area, the data is “cleansed” by removing 

latitude/longitude spatial details to prevent the identification of individual participants. This 

approach offers strong data protection while satisfying the needs of many users who simply 

require aggregated driving information or individual vehicle time versus speed profiles. The 

public download area allows these users quick and easy access to the data they need without 

requiring them to go through the more involved approval and connection procedure to access the 

secure portal environment. Security is also enhanced by providing these users access to only the 

data details they require. The next section of this paper provides additional information about 

these three TSDC sections.
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3. TSDC DATA HANDLING AND ORGANIZATION

3.1. TSDC Section 1: Secure Enclave for Storing and Processing Raw Data

NREL drew upon best-practice lessons from similar data-archiving activities to establish key 

TSDC features, including security such as physical building-badge access, an on-site security 

force, and individual account passwords; redundancy, including maintaining backup copies; and 

data handling, such as database management along with processing the data for quality control 

and information addition. With respect to data handling, significant parallel learning and 

cooperative development have occurred with the aforementioned commercial vehicle Fleet DNA 

project, which also works with extensive amounts of GPS data. Fig. 1 illustrates the processing 

procedure that has evolved to support both data projects.

Fig. 1. Shared data-processing procedures for Fleet DNA and the TSDC

Processing routine subcomponents that have evolved during the course of the TSDC and Fleet 

DNA projects include the initial steps to structure and standardize data formats. The latest update 

has been to transition from a traditional fixed-table database structure to a NoSQL data-storage 

approach. This change was motivated by the growing number of data sets and particularly data 

types being stored. Each archived study typically contains time-series data (e.g., recorded at onesecond intervals) that include time stamps, latitude/longitude coordinates, travel speeds, and 

measures of GPS quality, such as the number of satellites contributing to the coordinate 

determination. Study results are also summarized at trip and tour levels, as well as at the level of 

overall metadata (e.g., demographic information for participating households and vehicles, and

specific details on the original study). A traditional database structure worked well initially for 

Data Reporting
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storing these data, with satisfactory performance for the time it takes to read entire tables from 

the disk when sub-setting the data for various analyses; however, a growing number of columns 

within the data tables and a growing amount of variation or customization from study to study

leads to processing inefficiencies for traditional databases that require a fixed structure across all 

data tables.

One driver of data-channel variability among studies is the varied inclusion of parameters from 

participating vehicles’ on-board data bus. This is frequently the case for Fleet DNA data sets, 

and on-board data are also included in the TSDC, such as from a subsample of participants’ 

vehicles in the large 2010–2012 California Household Travel Survey [21]. The NoSQL approach 

organizes the data such that only the information needed for a particular subset analysis gets read 

off the disk, and it permits flexibility in the number of parameters stored for each study and each 

participant.

The next step in the processing routine following data organization and format standardization is 

GPS speed filtration. Anyone who has spent much time analyzing raw GPS driving data can 

readily appreciate the need for this quality-control step. Over the years, NREL has developed and 

refined techniques for identifying/correcting GPS measurement errors, which can result from 

equipment cold-starts (in which recording does not begin until after a vehicle/person has already 

started moving), signal dropouts, signal noise/jumps, and measurement drifts. If uncorrected, 

quality issues with the raw data can lead to unreasonable calculations of driving distances, 

speeds, and accelerations in second-by-second GPS data. In addition to enabling the processed 

GPS data to be used for things such as vehicle powertrain simulations, the quality-control steps 

have sometimes identified data-recording errors that had not been flagged from the original 

study. For example, in one study approximately 2% of trips were inadvertently assigned 

duplicate identification numbers, resulting in huge jumps in the GPS point recordings (actually 

made by two different vehicles driving across town from one another). In another study, 5% to 

10% of the GPS data-collection devices were inadvertently set to record speed data in kilometers 

per hour rather than miles per hour. When the data was interpreted in the expected unit of miles 

per hour, some of the vehicle speeds appeared high. The error was identified and corrected by 

comparing point-to-point distance calculations to the speed readings. Learning from these 

experiences, NREL developed several visualizations and quantitative metrics to monitor the 

automated quality-control routines themselves, which are used to flag data for manual inspection 

and to continually improve data-processing accuracy and speed.

In addition to quality-control processing, NREL performs several steps that add further value to 

the GPS travel profiles. These include providing accompanying reference information (e.g., 

geospatial economic, demographic, and land-use data) and linking the GPS points to underlying 

road network and elevation data (using reference layers from NAVTEQ/Nokia/HERE and from 

the U.S. Geological Survey, respectively). The data-linking processes require additional qualitycontrol steps but can produce useful information, such as the distribution of travel on different 

road types and relative utilization of specific roads in the network. NREL’s elevation linking and 

filtering procedure adds a road grade estimate to each GPS data point. It is described in more 

detail in separate publications [22], [23].
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3.2 TSDC Section 2: Public Download Area for Cleansed Data

Fig. 2 shows a screenshot of the TSDC website, from which cleansed versions of the data are 

publicly available for download. As described previously, the intent with the public download 

area is to make available data versions that do not have privacy concerns but that are sufficient 

for many applications. These data include aggregated statistics, trip-driving distances, and 

second-by-second vehicle-speed profiles (absent latitude/longitude coordinate details). Following 

guidance from the TSDC advisory committee, the public download area also excludes data such 

as vehicle model (though make and year are included, and car/truck class is appended when 

possible), because information on rare vehicle models could theoretically be combined with 

other data sources to violate the anonymity of an individual participant. The committee also 

recommended a cautious initial approach to exclude NREL’s point-by-point road-grade estimate 

from the cleansed data because of concerns about grade potentially being used to backfill 

latitude/longitude locations into some travel profiles. In addition to these data cautions, users are 

required to register and accept a point-and-click legal disclaimer and use agreement (also 

pictured in Fig. 2) stating that he/she will not attempt to identify individual or personal 

information from the data.

Fig. 2. TSDC website and downloadable cleansed data registration form [14]

After completing the simple registration form and logging in, users can view a more detailed 

summary description of the studies from which data has been made available. Several files are 

also readily available to download for each study. These typically consist of:

• The final report—Providing extensive details about the original study and the context of 

the collected data

• Multiple data files—Typically in comma-separated variable (.csv) format and generally 

including:
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o Detailed point-by-point travel data for each trip by each vehicle/participant 

throughout the entire study period, both in raw/original form and in a processed 

form with NREL’s quality-control and filtering routines applied.

o Demographic data on participants (bins for age, income, number of vehicles in 

household, etc.) and their vehicles (year, make, and vehicle class/fuel economy 

when possible).

• A data dictionary—Providing a general overview of the study and data, any issues of 

which to be aware, definitions of each variable in the downloadable data files, and 

summary statistics (about driving distances, speeds, etc.).

NREL, FHWA, and the TSDC advisory group also considered processing options to generate 

other types of cleansed data. One considered approach was to code trip ends to the centroid of a 

geographic region, such as a traffic analysis zone or TAZ. This would make some spatial data 

available for download, simply with obfuscated trip ends. However, this option was ultimately 

turned aside for failing to strike the desired balance between privacy protection and usability. 

Even partially obfuscated spatial data could present an added privacy concern when placed 

alongside other details such as driving speed/distance, household/vehicle demographics, and trip 

purpose [24]. Usability of the obfuscated spatial data would also be limited by the inability to 

link actual trip ends back to land-use information from sources such as parcel data and Google 

Maps. Instead, it was decided to provide only spatial data through the secure portal environment 

described below—relying on rigorous user screening, technical controls, and a legal agreement 

for privacy protection, and providing numerous geographic information system (GIS) tools and 

reference data to support user analyses within the environment.

3.3. TSDC Section 3: Secure Portal Environment for Detailed Data

While developing the operating details for the secure portal environment, NREL, FHWA, and 

the TSDC advisory group again considered what lessons could be drawn from related bestpractice examples. It was found that the National Household Travel Survey (NHTS) had 

established a process for researchers to request the “NHTS DOT file.” This example presented a

situation similar to the TSDC goals—permitting restricted access to greater geographic and 

demographic details from the original data (that could be abused to identify a participant) in 

order to permit legitimate research/analyses that could not otherwise be accomplished without 

the detailed data. The NHTS procedure requires users to describe the analysis they wish to 

conduct and sign a confidentiality agreement before receiving the detailed data. The TSDC 

adopted these as well as additional privacy-protection steps as summarized below:

• Applicants must complete an analysis description form describing:

o The analysis to be conducted

o Other data sources considered to support the analysis and why they are insufficient

o The output results the user anticipates wanting to remove from the secure 

environment

• Applicants must sign a data use and disclaimer agreement including:

o Confidential data-protection legal language

o An explicit pledge to not attempt to identify individual participants

o An additional signature required from his/her university advisor or line manager
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• Users must also complete a Condition of Use for Cyber Resources form before they may 

establish a connection account to the NREL virtual machines hosting secure portal 

environment

• After users complete the paperwork, the advisory group reviews the application and 

provides an access recommendation; DOT and NREL then make the final approval or 

denial decision

• Once approved, users may interface with the data only through the secure portal

environment:

o The environment prohibits data transfer (Clipboard sharing, local drive access, and 

internet connection are all disabled.)

o NREL reviews any externally developed user code or base files before loading 

them into the environment for use and similarly audits aggregated results that a 

user wishes to remove from the environment before providing them to the user.

With the secure portal environment, the TSDC created a more secure mechanism for controlled 

access to sensitive data than the approach of sending the data directly to approved users. 

Maintaining the data behind computer firewalls avoids the potential for intentional or 

unintentional re-sharing of the data to unauthorized users after giving an authorized user full 

control of a copy of the database.

Although operating within these security measures inevitably places some constraints on data 

users, NREL has also sought to include features and functions within the secure portal 

environment to enhance its usability for researchers. These efforts have included providing a 

variety of software tools to support a range of user preferences and abilities. The available 

software includes free and open-source tools for database query, programming, and analysis, 

such as PostgreSQL/PostGIS/QGIS, GRASS, Python, and R. The database-integrated free and 

open-source tools help provide computational efficiency for large GIS analyses (important when 

a data set contains millions of GPS data points), but they require some programming expertise. 

Users are therefore also given access to the commercial ArcGIS software from ESRI, which 

provides a user-friendly integrated system for working with GIS data through a graphical user 

interface.

To further support an assortment of spatial analyses, NREL has included a variety of additional 

GIS reference information in the secure portal environment. These data include Census 

Topologically Integrated Geographic Encoding and Referencing (TIGER) system files showing 

water bodies, roads, landmarks, and political boundaries (such as county, census tract, and block 

group). When available, additional reference details accompany specific data sets. For example, 

accompanying the Traffic Choices Study data, the TSDC also includes archived road speed and 

UrbanSIM data for the Puget Sound region (grid-based information about demographic, 

economic, and land-use characteristics) [25]. As mentioned earlier, users can ask NREL to load 

additional tools or reference files into the secure portal environment to support a particular 

analysis. Fig. 3 and Fig. 4 illustrate a few examples of the available tools and reference 

information.
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Fig. 3. TSDC software and supporting data resources

Fig. 4. Example of demographic, processed trip, and regional data available in the TSDC
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4. OPERATING THE TSDC—WORKING WITH DATA PROVIDERS AND USERS

In each year of its initial operation, the TSDC has gradually expanded the number of data sets 

that it houses and the number of users it supports. Some data providers were more willing than 

others to be among the earliest participants; but as the data set count and successful track record 

have grown, more and more providers have become interested in participating. Providers state 

that they appreciate being able to point interested users to the TSDC rather than individually 

hosting something similar and interfacing with users themselves. Some providers have also been 

motivated by the opportunity to leverage the processing, filtering, and data-addition 

functionalities that NREL has developed for TSDC data sets to take advantage of these 

enhancements to their own data.

Several of the data sets included in the TSDC were collected as add-on samples to traditional 

diary-based regional travel surveys for assessing issues such as trip underreporting. These GPS 

samples typically include second-by-second data for several hundred to several thousand 

vehicles and/or persons recorded from one day to one week. A few of the TSDC participants 

providing these types of data include the Atlanta Regional Commission, California Department 

of Transportation, Chicago Metropolitan Agency for Planning, Mid-America Regional Council, 

and Texas Department of Transportation. Altogether, the TSDC second-by-second vehicle-based 

data from these providers’ studies total more than one million miles of driving.

The aforementioned Traffic Choices Study conducted by the Puget Sound Regional Council 

represents another large data set hosted in the TSDC. The Traffic Choices Study collected data 

from 2004 to 2006 to evaluate travel behavior changes in response to time- and location-variable 

road tolling. The particular value of this data set is that it contains GPS data from more than 400 

vehicles spanning a period of 18 months, including baseline data collected prior to the 7-month 

experimental tolling period.

As the number of TSDC data sets has grown, so too has the user base of researchers accessing 

the data. NREL has correspondingly shifted some of the TSDC focus from the formational 

activities described in the previous sections to ongoing data center operations. These efforts 

include not only user support, but also leveraging user experiences and feedback to implement 

ongoing enhancements. The varied research topics that TSDC users have explored include travel 

time variability, driving behavior, mass transit opportunities, electrified vehicle analysis, 

emissions and air quality modeling, and vehicle design and durability testing. The TSDC website 

includes a subpage on “Data Application Examples” that further describes user research topics 

and provides links to completed publications that have leveraged GPS travel data [14].

In addition to this wide variety of research topics, NREL has found wide variability in user 

experience and comfort levels working with the data and with tools provided in the TSDC secure 

portal environment. Although many users can work fluently with database tools and open-source 

software, a number of others have little experience working with large databases and are more 

comfortable with commercial software packages. In an effort to better support more novice 

users, as well as provide increased convenience for all users, NREL has been developing feature 

enhancements in an interactive user manual and data-visualization tool for the secure portal 

environment.
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Fig. 5 displays images from this interactive tool, including a set of drop-down menus for quickly 

exploring data tables and their contents for each study. The tool also helps users to create basic 

graphs and to query database variables for visualization in the graphs without requiring any SQL 

programming knowledge. Users may additionally download preformatted reports using the tool.

Fig. 5. Images from the interactive user manual and data visualization tool for the TSDC secure portal environment

In addition to providing access to analysis tools and reference information, NREL staff field 

questions and help users get started with their analyses; however, NREL staff do not have an 

unlimited amount of time to support user projects, and ultimate responsibility falls to the users 

themselves to make sure they have the required skill sets and can perform the work necessary to 

accurately complete their analyses. To help users get started, NREL supplies example code for 

software tools within the secure portal environment that demonstrates basic functions such as 

querying data, performing calculations, and generating plots.

NREL currently does not charge any fees from TSDC users (or data providers) and hopes to 

continue operating without imposing such fees—simply relying upon the modest operating 

budget provided by DOT and DOE, along with leveraging operating efficiencies from NREL’s 

other sensitive data-archiving activities. One area in which budget limitations create a challenge 

for maximally supporting all users is that of making costly commercial software tools available 

in the secure portal environment. The expense for many tools can quickly become prohibitive to 

support network licenses accessible to all environment users. NREL has prioritized availability 

of an ArcGIS license given that software tool’s prevalence for GIS analysis, although only a 

single license seat is available so far. This limits the number of simultaneous secure portal users 

who can access the tool, which has become an occasional issue as the user base for this 

environment has grown (though there are no such limits on the open-source GIS tools available 
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in the environment). NREL does plan to add another ArcGIS license to help with this, and will 

continue exploring licensing options for other frequently requested commercial tools.

When it comes to the secure portal application process itself, the vast majority of researchers 

who have applied have ultimately been granted accounts to use the environment. The typical 

process after receiving a prospective user’s application includes an initial screening to check for 

missing items or insufficient answers. NREL and/or FHWA then iterate with the applicant to fill 

in any omissions and provide any needed elaboration, such as about the purpose, methods, or 

desired outputs of the proposed research or to clarify what can or cannot be removed from the 

secure portal environment. After the applicant submits any needed revisions, the remaining steps 

of advisory committee review/approval and user account creation typically take less than two 

weeks. The only occasions thus far when prospective users’ applications have not been approved 

involved situations in which the proposed analysis did not actually require access to the data in 

the secure portal environment, or when users were unable or unwilling to remedy incomplete 

items identified during the initial application screening. The full application packet and

instructions about the process are posted on the TSDC website [14].

Among the topics for future enhancements, NREL plans to establish a collaborative environment 

in which users can share results, communicate, and answer questions from each other. Initial 

indications suggest that current users would be receptive to such a concept, because several 

already expressed a willingness to share code and intermediate results that they have generated 

through the course of completing their analyses. New users will no doubt also benefit from the 

opportunity to leverage previous users’ experience to come up to speed more quickly and to 

build on others’ results.

5. SUMMARY

During the past 15 years, increasing numbers of organizations and planning agencies have begun 

collecting high-resolution GPS travel data. Despite the significant effort and expense to collect it, 

privacy concerns often lead to underutilization of the data. Through the TSDC effort described 

here, NREL, DOE, and DOT/FHWA have partnered to address these concerns, support the needs 

of numerous data-starved applications, and increase research returns from the original datacollection investment. The TSDC has been developed and organized with the intent to first and 

foremost preserve privacy, but to do so in a way that balances security with accessibility and 

usability of the data for legitimate research needs. The TSDC structure helps support this goal by 

providing a secure enclave with no external access for backing up and processing raw data, a

publicly-accessible website for downloading cleansed data, and a secure portal environment 

through which approved users can work with the detailed spatial data using a variety of tools and 

reference information.

The TSDC team applied lessons from best-practice examples at other data centers when 

developing the structure and operating procedures for the TSDC, and the team relies upon an 

advisory committee representing diverse stakeholder interests to endorse any procedure changes 

and to review applications from prospective secure portal environment users. Several years of 

operating the TSDC have also generated useful lessons in areas such as GPS data handling, 

processing, and user support. As the TSDC continues to grow, NREL will apply these and 
Gonder et al. – Archiving Data from New Survey Technologies

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This report is available at no cost from the National Renewable Energy Laboratory (NREL) at www.nrel.gov/publications.

ongoing lessons toward continual enhancements to better support the needs of data providers and 

TSDC users and to thus advance the research benefit derived from such valuable data.

6. ACKNOWLEDGEMENTS

The authors are grateful for initial start-up support for the TSDC provided by internal NREL 

funding and by the DOT FHWA Office of Operations, and also for continued support throughout 

the project from the DOT FHWA Office of Planning and the DOE Vehicle Technologies Office.

Further thanks go to Brennan Borlaug, Adam Duran, Arnaud Konan, Avinash Pallapu, and Eric 

Wood for their contributions toward GPS data processing, analysis, and user support, and to 

TSDC users for their helpful inputs and collaboration on continual project improvements.

NREL is managed and operated by the Alliance for Sustainable Energy under DOE Contract No. 

DE-AC36-08-GO28308.

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